AD 80-21-53
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Robinson Helicopter Company | R22 | Airworthiness Directives; ROBINSON HELICOPTER Model R-22 Helicopters |
Unsafe Condition
Tooth failure of the spiral bevel gear in the main rotor transmission and possible loss of power to the main rotor system.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect the main transmission gear teeth every 10 hours' time in service per SB-5. Remove transmission if spalling, cracks, or chips are found. Prohibit flight without operable MR chip detector system and perform pre-flight checks. Replace gear sets numbered 39 through 210 by January 31, 1981.
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Compliance Time
Prior to further flight unless already accomplished.
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Affected Aircraft
Robinson Helicopter Company Model R-22 Helicopters, fuselage numbers 0006 through 0060, with spiral bevel gear sets numbered 39 through 210 installed.
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Federal Register Abstract
Main Transmission Gears
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_80-21-53.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 80-21-53 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; ROBINSON HELICOPTER Model R-22 Helicopters Subject: Main Transmission Gears Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/18/1980 Make: Robinson Helicopter Company Model: R22 Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 80-21-53 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3989 AD NUMBER: 80-21-53 SUBJECT HEADING: Airworthiness Directives; ROBINSON HELICOPTER Model R-22 Helicopters ACTION: SUMMARY: DATES: Effective December 18, 1980. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 80-21-53 ROBINSON HELICOPTER: Amendment 39-3989. Applies to Model R-22 Helicopters, certified in all categories, fuselage numbers 0006 through 0060, with spiral bevel gear sets numbered 39 through 210 installed in the main rotor transmission. Compliance is required prior to further flight unless already accomplished. To prevent tooth failure of the spiral bevel gear in the main rotor transmission and possible loss of power to the main rotor system, accomplish the following: (a) Prior to further flight and at intervals not to exceed 10 hours' time in service thereafter, inspect the main transmission gear teeth in accordance with paragraph "Inspection Procedure" of Robinson Helicopter Company Mandatory Service Bulletin SB-5, dated October 6, 1980. (b) If gear tooth spalling, or cracks are detected, or if chips are found on the sump magnetic chip detector plug, remove the main transmission from service. (c) In the event that the MR (main rotor) chip light comes on during flight, make a precautionary landing as soon as possible and remove the transmission from service. (d) Flight is prohibited without an operable MR chip detector system. Prior to each flight the pilot must perform a MR chip light check by grounding the electrical terminal of the chip detector at the bottom of the main transmission and checking to be sure the MR light on the instrument panel illuminates. The pilot must be trained by a certified mechanic to perform this check. This check constitutes preventative maintenance and may be performed by persons authorized to perform preventative maintenance under FAR 43. The check required by this paragraph may be performed by the pilot. (e) All gear sets numbered 39 through 210 must be removed from service no later than January 31, 1981. Replacement of these gear sets constitutes terminating action for this AD. (f) Special flight permits may be issued, in accordance with FAR 21.197 and 21.199, to operate helicopters to a base for the accomplishment of inspections required by this AD. (g) Alternative inspections, modifications, or other actions which provide an equivalent level of safety may be used when approved by the Chief, Engineering and Manufacturing Branch, FAA Western Region. This amendment becomes effective December 18, 1980 to all persons, except those to whom it was made immediately effective by telegraphic AD T80-21-53, dated October 11, 1980. FOOTER:
Document Text
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AD Final Rules - DRS_80-21-53.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 80-21-53 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; ROBINSON HELICOPTER Model R-22 Helicopters Subject: Main Transmission Gears Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/18/1980 Make: Robinson Helicopter Company Model: R22 Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 80-21-53 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3989 AD NUMBER: 80-21-53 SUBJECT HEADING: Airworthiness Directives; ROBINSON HELICOPTER Model R-22 Helicopters ACTION: SUMMARY: DATES: Effective December 18, 1980. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 80-21-53 ROBINSON HELICOPTER: Amendment 39-3989. Applies to Model R-22 Helicopters, certified in all categories, fuselage numbers 0006 through 0060, with spiral bevel gear sets numbered 39 through 210 installed in the main rotor transmission. Compliance is required prior to further flight unless already accomplished. To prevent tooth failure of the spiral bevel gear in the main rotor transmission and possible loss of power to the main rotor system, accomplish the following: (a) Prior to further flight and at intervals not to exceed 10 hours' time in service thereafter, inspect the main transmission gear teeth in accordance with paragraph "Inspection Procedure" of Robinson Helicopter Company Mandatory Service Bulletin SB-5, dated October 6, 1980. (b) If gear tooth spalling, or cracks are detected, or if chips are found on the sump magnetic chip detector plug, remove the main transmission from service. (c) In the event that the MR (main rotor) chip light comes on during flight, make a precautionary landing as soon as possible and remove the transmission from service. (d) Flight is prohibited without an operable MR chip detector system. Prior to each flight the pilot must perform a MR chip light check by grounding the electrical terminal of the chip detector at the bottom of the main transmission and checking to be sure the MR light on the instrument panel illuminates. The pilot must be trained by a certified mechanic to perform this check. This check constitutes preventative maintenance and may be performed by persons authorized to perform preventative maintenance under FAR 43. The check required by this paragraph may be performed by the pilot. (e) All gear sets numbered 39 through 210 must be removed from service no later than January 31, 1981. Replacement of these gear sets constitutes terminating action for this AD. (f) Special flight permits may be issued, in accordance with FAR 21.197 and 21.199, to operate helicopters to a base for the accomplishment of inspections required by this AD. (g) Alternative inspections, modifications, or other actions which provide an equivalent level of safety may be used when approved by the Chief, Engineering and Manufacturing Branch, FAA Western Region. This amendment becomes effective December 18, 1980 to all persons, except those to whom it was made immediately effective by telegraphic AD T80-21-53, dated October 11, 1980. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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